ZXLD1366QET5TA [DIODES]
AUTOMOTIVE COMPLIANT HIGH ACCURACY 1A, 60V LED DRIVER;
| 型号： | ZXLD1366QET5TA |
| 厂家： | 
DIODES INCORPORATED |
| 描述： | AUTOMOTIVE COMPLIANT HIGH ACCURACY 1A, 60V LED DRIVER 驱动 |
| 文件： | 总32页 (文件大小：1490K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
ZXLD1366Q
AUTOMOTIVE COMPLIANT HIGH ACCURACY 1A, 60V LED DRIVER
Description
Pin Assignments
The ZXLD1366Q is
a continuous mode inductive step-down
(TOP VIEW)
converter, designed for driving single or multiple series connected
LEDs efficiently from a voltage source higher than the LED voltage.
The device operates from an input supply between 6V and 60V and
provides an externally adjustable output current of up to 1A.
1
2
VIN
LX
5
4
GND
The ZXLD1366Q uses a high-side output current sensing circuit
which uses an external resistor to set the nominal average output
current. The output current can be adjusted above or below the set
value by applying an external control signal to the 'ADJ' pin.
ISENSE
3
ADJ
TSOT25
(TOP VIEW)
Enhanced output current dimming resolution can be achieved by
VIN
6
LX
1
2
3
applying a PWM signal to the ‘ADJ’ pin.
5 GND
GND
ADJ
Soft-start can be forced using an external capacitor from the ADJ pin
to ground. Applying a voltage of 0.2V or lower to the ADJ pin turns
the output off and switches the device into a low current standby
state.
4
ISENSE
V-DFN3030-6
(TOP VIEW)
The ZXLD1366Q is qualified to AEC-Q100 Grade
Automotive Compliant supporting PPAPs.
1 and is
LX 1
VIN
8
7
6
5
Features
2
3
GND
GND
GND
GND
ISENSE
Typically Better than 0.8% Output Current Accuracy
Simple and With Low Part Count
4
ADJ
Single Pin On/Off and Brightness Control Using DC Voltage or
PWM
SO-8EP
PWM Resolution up to 1000:1
High Efficiency (up to 97%)
Typical Application Circuit
Switching Frequencies up to 1MHz
Wide Input Voltage Range: 6V to 60V
Inherent Open-Circuit LED Protection
Available in Thermally Enhanced Green Molding Packages
.
.
.
V-DFN3030-6
SO-8EP
JA = +44°C/W
JA = +45°C/W
JA = +82°C/W
TSOT25
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Qualified to AEC-Q100 Standards for High Reliability
PPAP Capable (Note 4)
Applications
Automotive Lighting:
.
.
.
Internal Door Lights
Rear Fog Lamps
Position Lights
Notes:
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3) compliant.
2. See https://www.diodes.com/quality/lead-free/ for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and
Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
4. Automotive products are AEC-Q100 qualified and are PPAP capable. Refer to https://www.diodes.com/quality/.
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Block Diagram
D1
V
IN
L1
RS
I
V
IN
5
4
SENSE
1
LX
5V
R1
C1
47µF
4
Voltage
regulator
-
+
0.2V
Lowvoltage
detector
-
+
MN
-
ADJ
+
3
R5
20K
R4
50K
600KHz
R2
R3
D1
1.25V
-
+
1.35V
GND
2
Figure 1. Pin Connection for TSOT25 Package
Pin Description
Name
LX
TSOT25
SO-8EP
1
V-DFN3030-6
Function
Drain of NDMOS switch
1
2
1
Ground (0V)
GND
2, 3, 6, 7
2, 5
Multi-function On/Off and brightness control pin:
•
Leave floating for normal operation. (VADJ = VREF = 1.25V giving nominal average
output current IOUTnom = 0.2V/RS
)
•
•
Drive to voltage below 0.2V to turn off output current
Drive with DC voltage (0.3V < VADJ < 2.5V) to adjust output current from 25% to
200% of IOUTnom
ADJ
3
4
3
•
Connect a capacitor from this pin to ground to set soft-start time.
Soft start time increases approximately 0.2ms/nF
Connect resistor RS from this pin to VIN to define nominal average output current IOUTnom
= 0.2V/RS
.
ISENSE
4
5
5
8
4
6
(Note: RSMIN = 0.2V with ADJ pin open-circuit)
Input Voltage (6V to 60V). Decouple to ground with 4.7µF of higher X7R ceramic
capacitor close to device.
VIN
Exposed Pad (EP) - connected to device substrate.
To improve thermal impedance of package the EP must be connected to power ground
but should not be used as the 0V (GND) current path.
Pad
Pad
Pad
It can be left floating but must not be connected to any other voltage other than 0V.
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Absolute Maximum Ratings (Note 5) (@TA = +25°C, unless otherwise specified.)
Symbol
VIN
Parameter
Rating
-0.3 to +65
+0.3 to -5
-0.3 to +65
-0.3 to +6
1.25
Unit
V
Input Voltage
V
VSENSE
VLX
VADJ
ILX
ISENSE Voltage (Note 6)
LX Output Voltage
Adjust Pin Input Voltage
Switch Output Current
V
V
A
TSOT25
1
Power Dissipation
(Refer to Package Thermal De-rating Curve on SO-8EP
Page 25)
2.2
W
PTOT
V-DFN3030-6
1.8
Operating Temperature
Storage Temperature
Junction Temperature
-40 to +125
° C
° C
° C
TOP
TST
-55 to +150
+150
SO-8EP
<250
TJ MAX
ESD Susceptibility
TSOT25
<250 (Note 7)
1000
V-DFN3030-6
—
V
HBM
CDM
Human Body Model
500
Charged Device Model
1000
1000
V
Notes:
5. All voltages unless otherwise stated are measured with respect to GND.
6. VSENSE is measured with respect to VIN.
7. Although value is reduced, no physical change to device.
Caution:
Stresses greater than the 'Absolute Maximum Ratings' specified above may cause permanent damage to the device. These are stress ratings only;
functional operation of the device at conditions between maximum recommended operating conditions and absolute maximum ratings is not implied.
Device reliability may be affected by exposure to absolute maximum rating conditions for extended periods of time.
Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling
and transporting these devices.
The human body model is a 100pF capacitor discharge through a 1.5kΩ resistor pin.
Thermal Resistance
Rating
Symbol
Parameter
Unit
TSOT25
SO-8EP
V-DFN3030-6
45
—
7
JA
JB
JC
Junction to Ambient
Junction to Board
Junction to Case
82
33
—
44
—
°C/W
14
Recommended Operating Conditions
Symbol
VIN
Parameter
Min
6
Max
60
Unit
V
Input Voltage (Note 8)
Maximum Recommended Continuous/RMS Switch Current
—
1
A
ILX
External Control Voltage Range on ADJ Pin for DC Brightness Control (Note 9)
DC Voltage on ADJ Pin to Ensure Devices is Off
Minimum Switch Off-time
0.3
—
2.5
V
VADJ
0.25
800
800
625
0.99
0.7
V
VADJOFF
tOFFMIN
tONMIN
fLX MAX
DLX
—
ns
ns
kHz
—
—
° C
—
Minimum Switch On-time
—
Recommended Maximum Operating Frequency (Note 10)
Duty Cycle Range
0.01
0.3
-40
DLX(LIMIT) Recommended Duty Cycle Range of Output Switch at fLXMAX
Operating Temperature Range (Junction and Ambient)
+125
TOP
Notes:
8. VIN > 16V to fully enhance output transistor. Otherwise out current must be derated - see graphs. Operation at low supply may cause excessive heating
due to increased on-resistance.
9. 100% brightness corresponds to VADJ = VADJ(nom) = VREF. Driving the ADJ pin above VREF will increase the VSENSE threshold and output current
proportionally.
10. ZXLD1366Q will operate at higher frequencies but accuracy will be affected due to propagation delays.
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Electrical Characteristics (Test conditions: (@ VIN = 24V, TA = +25°C, unless otherwise specified.))
Symbol
VSU
Parameter
Condition
Min
—
Typ
4.85
4.75
65
Max
5.20
—
Unit
V
—
—
Internal Regulator Start-up Threshold
Internal Regulator Shutdown Threshold
Quiescent Supply Current With Output Off
4.40
—
V
VSD
ADJ pin grounded
108
µ A
IINQoff
ADJ pin floating, L = 68µH,
3 LEDs, f = 260kHz
Quiescent Supply Current With Output Switching
(Note 12)
—
1.6
—
mA
IINQon
Measured on ISENSE pin with
respect to VIN VADJ = 1.25V;
VIN = 18V
Mean Current Sense Threshold Voltage
(Defines LED Current Setting Accuracy)
195
200
205
mV
VSENSE
Sense Threshold Hysteresis
ISENSE Pin Input Current
—
—
—
15
4
—
%
VSENSEHYS
ISENSE
10
µ A
VSENSE = VIN -0.2V
Measured on ADJ pin with pin
floating
Internal Reference Voltage
—
—
1.25
50
—
—
V
ppm/°C
V
VREF
VREF/T
VADJ
—
Temperature Coefficient of VREF
External Control Voltage Range on ADJ Pin for DC —
0.3
—
2.5
Brightness Control (Note 11)
DC Voltage on ADJ Pin to Switch Device from
Active (On) State to Quiescent (Off) State
0.15
0.20
0.20
0.25
0.27
0.30
V
V
VADJoff
VADJon
VADJ falling
DC Voltage on ADJ Pin to Switch Device from
Quiescent (Off) State to Active (On) State
VADJ rising
0 < VADJ < VREF
VADJ > VREF +100mV
—
30
50
65
kΩ
RADJ
Resistance between ADJ Pin and VREF
10.4
14.2
18.0
Continuous LX Switch Current
LX Switch ‘On’ Resistance
LX Switch Leakage Current
—
—
—
—
0.50
—
1
0.75
5
A
Ω
ILXmean
RLX
@ ILX = 1A
—
µ A
ILX(leak)
PWM frequency < 300Hz PWM
amplitude = VREF
Duty Cycle Range of PWM Signal Applied to ADJ
Pin during Low Frequency PWM Dimming Mode
0.001
—
1.000
V
DPWM(LF)
Measured on ADJ pin
—
Brightness Control Range
—
—
—
1000:1
5:1
—
—
—
—
DC Brightness Control Range
(Note 13)
DCADJ
Time taken for output current to
reach 90% of final value after
voltage on ADJ pin has risen
above 0.3V. Requires external
capacitor 22nF. See graphs for
more details
Soft-start Ttime
—
2
—
ms
tSS
ADJ pin floating
L = 68µH (0.2V)
Operating Frequency
—
260
—
kHz
fLX
(See Graphs for More Details)
IOUT = 1A @ VLED = 3.6V
Driving 3 LEDs
Minimum Switch ‘ON’ Time
Minimum Switch ‘OFF’ Time
LX switch ‘ON’
LX switch ‘OFF’
—
—
130
70
—
—
ns
ns
tONmin
tOFFmin
Notes: 11. 100% brightness corresponds to VADJ = VADJ(nom) = VREF. Driving the ADJ pin above VREF will increase the VSENSE threshold and output current
proportionally.
12. Static current of device is approximately 700µA, see graph, Page 15.
13. Ratio of maximum brightness to minimum brightness before shutdown VREF = 1.25/0.3. VREF externally driven to 2.5V, ratio 10:1.
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Device Description
The device, in conjunction with the coil (L1) and current sense resistor (RS), forms a self-oscillating continuous-mode buck converter.
Device Operation
(Refer to Figure 1 Block diagram and Figure 2 Operating waveforms)
VIN
LX voltage
0V
VIN
tOFF
tON
230mV
170mV
200mV
SENSE voltage
VSENSE-
VSENSE+
IOUTnom +15%
IOUTnom
Coil current
IOUTnom -15%
0V
0.15VADJ
Comparator
input voltage
VADJ
0.15VADJ
5V
Comparator
output
0V
Figure 2. Theoretical Operating Waveforms
Operation can be understood by assuming that the ADJ pin of the device is unconnected and the voltage on this pin (VADJ) appears directly at the
(+) input of the comparator.
When input voltage VIN is first applied, the initial current in L1 and RS is zero and there is no output from the current sense circuit. Under this
condition, the (-) input to the comparator is at ground and its output is high. This turns MN on and switches the LX pin low, causing current to flow
from VIN to ground, via RS, L1 and the LED(s). The current rises at a rate determined by VIN and L1 to produce a voltage ramp (VSENSE) across RS.
The supply referred voltage VSENSE is forced across internal resistor R1 by the current sense circuit and produces a proportional current in internal
resistors R2 and R3. This produces a ground referred rising voltage at the (-) input of the comparator. When this reaches the threshold voltage
(VADJ), the comparator output switches low, and MN turns off. The comparator output also drives another NMOS switch, which bypasses internal
resistor R3 to provide a controlled amount of hysteresis. The hysteresis is set by R3 to be nominally 15% of VADJ
.
When MN is off, the current in L1 continues to flow via D1 and the LED(s) back to VIN. The current decays at a rate determined by the LED(s) and
diode forward voltages to produce a falling voltage at the input of the comparator. When this voltage returns to VADJ, the comparator output
switches high again. This cycle of events repeats, with the comparator input ramping between limits of VADJ 15%.
Switching Thresholds
With VADJ = VREF, the ratios of R1, R2 and R3 define an average VSENSE switching threshold of 200mV (measured on the ISENSE pin with respect
to VIN). The average output current IOUTnom is then defined by this voltage and RS according to:
IOUTnom = 200mV/RS
Nominal ripple current is 30mV/RS.
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Device Description (Cont.)
Actual operating waveforms
VIN = 15V, RS = 0.2Ω, L = 68µH Normal Operation.
Output Current (Ch. 3) and LX Voltage (Ch. 2)
VIN = 30V, RS = 0.2Ω, L = 68µH Normal Operation.
Output Current (Ch. 3) and LX Voltage (Ch. 2)
VIN = 60V, RS = 0.2Ω, L = 68µH Normal Operation.
Output Current (Ch. 3) and LX Voltage (Ch. 2)
Adjusting Output Current
The device contains a low pass filter between the ADJ pin and the threshold comparator and an internal current limiting resistor (50kΩ nom)
between ADJ and the internal reference voltage. This allows the ADJ pin to be overdriven with either DC or pulse signals to change the VSENSE
switching threshold and adjust the output current.
Details of the different modes of adjusting output current are given in the applications section.
Output Shutdown
The output of the low pass filter drives the shutdown circuit. When the input voltage to this circuit falls below the threshold (0.2V nom.), the
internal regulator and the output switch are turned off. The voltage reference remains powered during shutdown to provide the bias current for
the shutdown circuit. Quiescent supply current during shutdown is nominally 60μA and switch leakage is below 5μA.
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Typical Operating Conditions
1.100
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
1.080
11 LEDs
13 LEDs
15 LEDs
1.060
1.040
1.020
1.000
0.980
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Output Current, L = 68µ H
10
8
6
4
2
0
-2
-4
-6
-8
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
-10
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Output Current Deviation, L = 68µ H
100
95
90
85
80
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
75
70
65
60
55
50
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Efficiency, L = 68µ H
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Typical Operating Conditions (Cont.)
500
1 LED
450
400
350
300
250
200
150
100
50
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
0
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Switching Frequency, L = 68µ H
100
90
80
70
60
50
40
30
20
10
0
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Duty Cycle, L = 68µ H
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Typical Operating Conditions (Cont.)
1.100
1 LED
3 LEDs
1.080
5 LEDs
7 LEDs
9 LEDs
1.060
1.040
1.020
1.000
11 LEDs
13 LEDs
15 LEDs
0.980
0.960
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Output Current, L = 100µ H
10
8
6
4
2
0
-2
-4
-6
-8
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
-10
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Output Current Deviation, L = 100µ H
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Efficiency, L = 100µ H
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Typical Operating Conditions (Cont.)
500
1 LED
3 LEDs
450
5 LEDs
7 LEDs
400
11 LEDs
350
13 LEDs
15 LEDs
300
250
200
150
100
50
0
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Switching Frequency, L = 100µ H
100
90
80
70
60
50
40
30
20
10
0
1 LED
3 LEDs
5 LEDs
7 LEDs
11 LEDs
13 LEDs
15 LEDs
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Duty Cycle, L = 100µ H
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Typical Operating Conditions (Cont.)
1.100
1 LED
3 LEDs
5 LEDs
1.080
7 LEDs
9 LEDs
11 LEDs
13 LEDs
1.060
15 LEDs
1.040
1.020
1.000
0.980
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Output Current, L = 150µ H
10
8
6
4
2
0
-2
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
-4
-6
-8
-10
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Output Current Deviation, L = 150µ H
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Efficiency, L = 150µ H
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Typical Operating Conditions (Cont.)
500
1 LED
450
400
350
300
250
200
3 LEDs
5 LEDs
7 LEDs
11 LEDs
13 LEDs
15 LEDs
150
100
50
0
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Switching Frequency, L = 150µ H
100
90
80
70
60
50
40
30
20
10
0
1 LED
3 LEDs
5 LEDs
7 LEDs
11 LEDs
13 LEDs
15 LEDs
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Duty Cycle, L = 150µ H
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ZXLD1366Q
Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Typical Operating Conditions (Cont.)
1.100
1 LED
3 LEDs
5 LEDs
1.080
7 LEDs
9 LEDs
11 LEDs
13 LEDs
1.060
15 LEDs
1.040
1.020
1.000
0.980
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Output Current, L = 220µ H
10
8
6
4
2
0
-2
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
-4
-6
-8
-10
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Output Current Deviation, L = 220µ H
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Efficiency, L = 220µ H
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ZXLD1366Q
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ZXLD1366Q
Typical Operating Conditions (Cont.)
500
1 LED
3 LEDs
450
5 LEDs
7 LEDs
400
11 LEDs
350
13 LEDs
15 LEDs
300
250
200
150
100
50
0
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Switching Frequency, L = 220µ H
100
90
80
70
60
50
40
30
20
10
0
1 LED
3 LEDs
5 LEDs
7 LEDs
11 LEDs
13 LEDs
15 LEDs
0
10
20
30
40
50
60
SUPPLY VOLTAGE (V)
Duty Cycle, L = 220µ H
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Document number: DS37078 Rev. 2 - 2
ZXLD1366Q
Typical Operating Conditions (Cont.)
1200
800
700
600
500
R = 300m
1000
R = 200m
800
R = 680m
600
400
200
0
400
300
200
100
0
0
1
2
3
0
10
20
30
40
50
60
70
ADJ PIN VOLTAGE (V)
LED Current vs. ADJ
SUPPLY VOLTAGE (V)
1.2430
1.2425
1.2420
1.2415
90
80
70
60
1.2410
50
40
30
20
1.2405
1.2400
1.2395
1.2390
10
0
1.2385
1.2380
0
10
20
30
40
50
60
70
0
10
20
30
40
50
60
70
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
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Typical Operating Conditions (Cont.)
1.6
1.4
1.2
-40° C
20° C
150° C
1.0
0.8
0.6
0.4
0.2
0
0
5
10
15
SUPPLY VOLTAGE (V)
LX On-Resistance vs. Supply Voltage
20
25
30
35
1.262
7V
9V
1.260
1.258
1.256
12V
20V
30V
1.254
1.252
1.250
1.248
1.246
1.244
-50
0
50
100
150
200
TEMPERATURE
(° C )
VADJ vs. Temperature
1.6
1.4
7V
9V
12V
20V
30V
1.2
1.0
0.8
0.6
0.4
0.2
0
-50
0
50
100
150
200
DIE TEMPERATURE
(° C )
LX On-Resisitance vs. Die Temperature
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Application Information
Setting Nominal Average Output Current with External Resistor RS
The nominal average output current in the LED(s) is determined by the value of the external current sense resistor (RS) connected between VIN
and ISENSE and is given by:
IOUTnom = 0.2/RS for RS ≥ 0.2Ω
The table below gives values of nominal average output current for several preferred values of current sense resistor (RS) in the typical application
circuit shown on page 1:
Nominal Average Output
RS (Ω)
Current (mA)
0.20
0.27
0.56
1,000
740
357
The above values assume that the ADJ pin is floating and at a nominal voltage of VREF (= 1.25V). Note that RS = 0.2Ω is the minimum allowed
value of sense resistor under these conditions to maintain switch current below the specified maximum value.
It is possible to use different values of RS if the ADJ pin is driven from an external voltage (see next section).
Output Current Adjustment by External DC Control Voltage
The ADJ pin can be driven by an external DC voltage (VADJ), as shown, to adjust the output current to a value above or below the nominal
average value defined by RS.
The nominal average output current in this case is given by:
IOUTdc = (VADJ /1.25) x (0.2/RS) for 0.3 < VADJ < 2.5V
Note that the 100% brightness setting corresponds to VADJ = VREF. When driving the ADJ pin above 1.25V, RS must be increased in proportion to
prevent IOUTdc exceeding 1A maximum.
The input impedance of the ADJ pin is 50kΩ ±25% for voltages below VREF and 14.2kΩ ±25% for voltages above VREF +100mV.
Output Current Adjustment by PWM Control
Directly Driving ADJ Input
A Pulse Width Modulated (PWM) signal with duty cycle DPWM can be applied to the ADJ pin, as shown below, to adjust the output current to a
value above or below the nominal average value set by resistor RS:
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Application Information (Cont.)
Driving the ADJ Input via Open Collector Transistor
The recommended method of driving the ADJ pin and controlling the amplitude of the PWM waveform is to use a small NPN switching transistor
as shown below:
This scheme uses the 50k resistor between the ADJ pin and the internal voltage reference as a pull-up resistor for the external transistor.
Driving the ADJ Input from a Microcontroller
Another possibility is to drive the device from the open-drain output of a microcontroller. The diagram below shows one method of doing this:
If the NMOS transistor within the microcontroller has high Gate / Drain capacitance, this arrangement can inject a negative spike into the ADJ
input of the ZXLD1366Q and cause erratic operation, but the addition of a Schottky clamp diode (eg Diodes Incorporated SD103CWS) to ground
and inclusion of a series resistor (3.3k) will prevent this. See the section on PWM dimming for more details of the various modes of control using
high frequency and low frequency PWM signals.
Shutdown Mode
Taking the ADJ pin to a voltage below 0.2V for more than approximately 100μs will turn off the output and supply current to a low standby level of
65μA nominal.
Note that the ADJ pin is not a logic input. Taking the ADJ pin to a voltage above VREF will increase output current above the 100% nominal
average value. (See page 15 graphs for details).
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Application Information (Cont.)
Soft-Start
An external capacitor from the ADJ pin to ground will provide a soft-start delay by increasing the time taken for the voltage on this pin to rise to the
turn-on threshold and by slowing down the rate of rise of the control voltage at the input of the comparator. Adding capacitance increases this
delay by approximately 0.2ms/nF. The graph below shows the variation of soft-start time for different values of capacitor.
16
14
12
10
8
6
4
2
0
-2
0
20
40
CAPACITANCE (nF)
Soft-Start Time vs. Capacitance form ADJ to Ground
60
80
100
120
Actual Operating Waveform [VIN = 60V, RS = 0.2Ω, L = 68μH, 22nF on ADJ]
Soft-start operation, LX voltage (CH2) and Output current (CH3) using a 22nF external capacitor on the ADJ pin.
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Application Information (Cont.)
VIN Capacitor Selection
A low ESR capacitor should be used for input decoupling, as the ESR of this capacitor appears in series with the supply source impedance and
lowers overall efficiency. This capacitor has to supply the relatively high peak current to the coil and smooth the current ripple on the input supply.
To avoid transients into the IC, the size of the input capacitor will depend on the VIN voltage:
VIN = 6 to 40V, CIN = 2.2μF
VIN = 40 to 50V, CIN = 4.7μF
VIN = 50 to 60V, CIN = 10μF
When the input voltage is close to the output voltage, the input current increases which puts more demand on the input capacitor. The minimum
value of 2.2μF may need to be increased to 4.7μF; higher values will improve performance at lower input voltages, especially when the source
impedance is high. The input capacitor should be placed as close as possible to the IC.
For maximum stability over temperature and voltage, capacitors with X7R, X5R, or better dielectric is recommended. Capacitors with Y5V dielectric
are not suitable for decoupling in this application and should not be used.
When higher voltages are used with the CIN = 10μF, an electrolytic capacitor can be used provided that a suitable 1µF ceramic capacitor is also
used and positioned as close to the VIN pin as possible.
A suitable capacitor would be NACEW100M1006.3x8TR13F (NIC Components).
The following web sites are useful when finding alternatives:
www.murata.com
www.niccomp.com
www.kemet.com
Inductor Selection
Recommended inductor values for the ZXLD1366Q are in the range 68μH to 220μH.
Higher values of inductance are recommended at higher supply voltages in order to minimize errors due to switching delays, which result in
increased ripple and lower efficiency. Higher values of inductance also result in a smaller change in output current over the supply voltage range
(see graphs pages 7-14). The inductor should be mounted as close to the device as possible with low resistance connections to the LX and VIN
pins.
The chosen coil should have a saturation current higher than the peak output current and a continuous current rating above the required mean
output current.
Suitable coils for use with the ZXLD1366Q may be selected from the MSS range manufactured by Coilcraft, or the NPIS range manufactured by
NIC components. The following websites may be useful in finding suitable components.
www.coilcraft.com
www.niccomp.com
www.wuerth-elektronik.de
The inductor value should be chosen to maintain operating duty cycle and switch 'on'/'off' time within the specified limits over the supply voltage
and load current range.
Figures 3, 4 and 5 (below), can be used to select a recommended inductor based on maintaining the ZXLD1366Q case temperature below +60°C.
For detailed performance characteristics for the inductor values 68, 100, 150 and 220μH see graphs on pages 7-14.
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Application Information (Cont.)
Minimum Recommended Inductor
2% Accuracy, <60°C Case Temperature
15
Legend
68uH
14
13
12
11
10
100uH
150uH
220uH
9
8
7
6
5
4
3
2
1
0
10
20
30
40
50
60
Supply Voltage (V)
Figure 3. ZXLD1366Q Minimum Recommended Inductor (TSOT25)
TC < 70° C , ILED = 1A
15
14
13
12
11
10
9
Legend
47µH
68µH
100µH
150µH
8
7
6
150µH
5
100µH
4
68µH
47µH
3
2
1
0
10
20
30
40
50
60
Supply Voltage (V)
Figure 4. ZXLD1366Q Minimum Recommended Inductor (SO-8EP)
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Application Information (Cont.)
M inim um R ecom m ended Inductor
2% Accuracy, <60°C Case Temperature
16
Legend
68µH
15
14
13
12
11
10
9
100µH
150µH
220µH
8
7
6
5
4
3
2
1
0.00
10.00
20.00
30.00
40.00
50.00
60.00
Supply Voltage (V)
Figure 5. ZXLD1366Q Minimum Recommended Inductor (V-DFN3030-6)
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Application Information (Cont.)
Diode Selection
For maximum efficiency and performance, the rectifier (D1) should be a fast, low capacitance Schottky diode* with low reverse leakage at the
maximum operating voltage and temperature.
They also provide better efficiency than silicon diodes, due to a combination of lower forward voltage and reduced recovery time.
It is important to select parts with a peak current rating above the peak coil current and a continuous current rating higher than the maximum output
load current. It is very important to consider the reverse leakage of the diode when operating above +85°C. Excess leakage will increase the power
dissipation in the device and if close to the load may create a thermal runaway condition.
The higher forward voltage and overshoot due to reverse recovery time in silicon diodes will increase the peak voltage on the LX output. If a silicon
diode is used, care should be taken to ensure that the total voltage appearing on the LX pin including supply ripple, does not exceed the specified
maximum value.
*A suitable Schottky diode would be PDS3100Q (Diodes Incorporated)
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Application Information (Cont.)
Reducing Output Ripple
Peak-to-peak ripple current in the LED(s) can be reduced if required, by shunting a capacitor Cled across the LED(s) as shown below:
Figure 6. Reduced Output Ripple
A value of 1µF will reduce the supply ripple current by a factor of three (approximately). Proportionally, lower ripple can be achieved with higher
capacitor values. Note that the capacitor will not affect operating frequency or efficiency, but will increase start-up delay by reducing the rate of
rise of LED voltage.
By adding this capacitor, the current waveform through the LED(s) changes from a triangular ramp to a more sinusoidal version without altering
the mean current value.
Operation at Low Supply Voltage
Below the undervoltage lockout threshold (VSD), the drive to the output transistor is turned off to prevent device operation with excessive on-
resistance of the output transistor. The output transistor is not fully enhanced until the supply voltage exceeds approximately 17V. At supply
voltages between VSD and 17V, care must be taken to avoid excessive power dissipation due to the on-resistance.
Note that when driving loads of two or more LEDs, the forward drop will normally be sufficient to prevent the device from switching below
approximately 6V. This will minimize the risk of damage to the device.
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Application Information (Cont.)
Thermal Considerations
When operating the device at high ambient temperatures, or when driving maximum load current, care must be taken to avoid exceeding the
package power dissipation limits. The graph below gives details for power derating. This assumes the device to be mounted on a 25mm2 PCB
with 1oz copper standing in still air.
Maximum Power Dissipation
Note that the device power dissipation will most often be a maximum at minimum supply voltage. It will also increase if the efficiency of the circuit
is low. This may result from the use of unsuitable coils, or excessive parasitic output capacitance on the switch output.
In order to maximize the thermal capabilities of the SO-8EP package, thermal vias should be incorporated into the PCB. See figure 7 for
examples used in the ZXLD1366Q evaluation boards.
Figure 7. Suggested Layout for SO-8EP Package
Vias ensure an effective path to the ground plane for the heat flow therefore reducing the thermal impedance between junction and ambient
temperature. Diodes Incorporated came to the conclusion that the compromise is reached by using more than 10 vias with 1mm of diameter and a
0.5 hole size.
The use of vias for the TSOT25 package should also be implemented to guarantee an effective thermal path.
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Application Information (Cont.)
Thermal Compensation of Output Current
High luminance LEDs often need to be supplied with a temperature compensated current in order to maintain stable and reliable operation at all
drive levels. The LEDs are usually mounted remotely from the device so, for this reason, the temperature coefficients of the internal circuits for the
ZXLD1366Q is optimized to minimize the change in output current when no compensation is employed. If output current compensation is required,
it is possible to use an external temperature sensing network normally, using Negative Temperature Coefficient (NTC) thermistors and/or diodes,
mounted very close to the LED(s). The output of the sensing network can be used to drive the ADJ pin in order to reduce output current with
increasing temperature.
Layout Considerations
LX Pin
The LX pin of the device is a fast switching node, so PCB tracks should be kept as short as possible. To minimize ground 'bounce', the ground pin
of the device should be soldered directly to the ground plane.
Coil and Decoupling Capacitors and Current Sense Resistor
It is particularly important to mount the coil and the input decoupling capacitor as close to the device pins as possible to minimize parasitic
resistance and inductance, which will degrade efficiency. It is also important to minimize any track resistance in series with current sense resistor
RS. It is best to connect VIN directly to one end of RS and ISENSE directly to the opposite end of RS with no other currents flowing in these tracks. It
is important that the cathode current of the Schottky diode does not flow in a track between RS and VIN as this may give an apparent higher
measure of current than is actually present, because of track resistance.
ADJ Pin
The ADJ pin is a high-impedance input for voltages up to 1.35V, so when left floating, PCB tracks to this pin should be as short as possible to
reduce noise pickup. A 100nF capacitor from the ADJ pin to ground will reduce frequency modulation of the output under these conditions. An
additional series 3.3kΩ resistor can also be used when driving the ADJ pin from an external circuit. This resistor will provide filtering for low-
frequency noise and provide protection against high-voltage transients.
High-Voltage Tracks
Avoid running any high-voltage tracks close to the ADJ pin to reduce the risk of leakage currents due to board contamination. The ADJ pin is soft-
clamped for voltages above 1.35V to desensitize it to leakage that might raise the ADJ pin voltage and cause excessive output current. However, a
ground ring placed around the ADJ pin is recommended to minimize changes in output current under these conditions.
Evaluation PCB
ZXLD1366Q evaluation boards are available upon request. Terminals allow users to interface the boards to their preferred LED products.
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Application Information (Cont.)
Dimming Output Current Using PWM
Low Frequency PWM Mode
When the ADJ pin is driven with a low frequency PWM signal (eg 100Hz), with a high-level voltage VADJ and a low level of zero, the output of the
internal low-pass filter will swing between 0V and VADJ, causing the input to the shutdown circuit to fall below its turn-off threshold (200mV nom),
when the ADJ pin is low. This will cause the output current to be switched on and off at the PWM frequency, resulting in an average output current
IOUTavg proportional to the PWM duty cycle.
(See Figure 8 - Low frequency PWM operating waveforms).
The average value of output current in this mode is given by:
IOUTavg 0.2DPWM/RS [for DPWM >0.001]
This mode is preferable if optimum LED 'whiteness' is required. It will also provide the widest possible dimming range (approx. 1000:1) and higher
efficiency at the expense of greater output ripple.
VADJ
tON
tOFF
PWM Voltage
0V
IOUTnom
0.2/Rs
Output Current
IOUTavg
0
Figure 8. Low Frequency PWM Operating Waveforms
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Application Information (Cont.)
Fault Condition Operation
The ZXLD1366Q has by default, open LED protection. If the LEDs should become open circuit, the ZXLD1366Q will stop oscillating; the ISENSE
pin will rise to VIN and the LX pin will then fall to GND. No excessive voltages will be seen by the ZXLD1366Q.
If the LEDs should become shorted together, the ZXLD1366Q will continue to switch, however, the duty cycle at which it will operate will change
dramatically and the switching frequency will most likely decrease. The on-time of the internal power MOSFET switch will be significantly
reduced because almost all of the input voltage is now developed across the inductor. The off-time will be significantly increased because the
reverse voltage across the inductor is now just the Schottky diode voltage (See Figure 9) causing a much slower decay in inductor current.
During this condition, the inductor current will remain within its controlled levels and so no excessive heat will be generated within the
ZXLD1366Q.
Figure 9. Switching Characteristics (Normal Open to Short LED Chain)
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Ordering Information
Pack
Code
Reel Size Reel Width Quantity
Per Reel
3,000
Qualification
(Note 15)
Packaging
(Note 14)
Part Number
Suffix
Part Number
(inches)
(mm)
ZXLD1366QDACTC
ZXLD1366QEN8TC
ZXLD1366QET5TA
V-DFN3030-6
SO-8EP
DAC
EN8
ET5
13
13
7
8
12
8
TC
TC
TA
Automotive Compliant
Automotive Compliant
Automotive Compliant
2,500
TSOT25
3,000
Notes:
14. For packaging details, go to our website at https://www.diodes.com/design/support/packaging/diodes-packaging/.
15. ZXLD1366Q has been qualified to AEC-Q100 grade 1 and is classified as “Automotive Compliant” supporting PPAP documentation. See ZXLD1366
datasheet for commercial qualified versions.
Marking Information
(1) TSOT25
1366 : Identification Code
(2) V-DFN3030-6
ZXLD1366 : Part Number
YY : Year : 17, 18, 19~
WW : Week : 01 to 52; 52 represents weeks 52 and 53
(3) SO-8EP
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Package Outline Dimensions
Please see http://www.diodes.com/package-outlines.html for the latest version.
1) Package Type : TSOT25
D
e1
01( 4x)
TSOT25
Min Max
1.00
0.01 0.10
0.84 0.90
0.30 0.45
0.12 0.20
Dim
A
A1
A2
b
Typ
-
-
-
-
E1/2
-
E/2
c
E1
E
Gauge Plane
Seating Plane
c
-
0
D
E
E1
e
e1
L
L2
θ
θ1
-
-
-
-
-
-
2.90
2.80
1.60
L
L2
0.95 BSC
1.90 BSC
01( 4x)
e
b
0.30 0.50
0.25 BSC
8°
12°
A2
A1
0°
4°
4°
-
A
All Dimensions in mm
Seating Plane
2) Package Type: V-DFN3030-6
A1
V-DFN3030-6
Dim Min Max
A3
Typ
A
A1
A3
b
D
D2
E
E2
e
e1
L
0.80 0.90
0.85
-
Seating Plane
0
-
0.05
-
A
D
0.203
0.35
3.00
2.00
3.00
1.20
0.95
1.90
0.50
e
0.30 0.40
2.95 3.05
1.95 2.05
2.95 3.05
1.15 1.25
L
D2
E
E2
-
-
-
-
0.45 0.55
Pin #1 ID
Chamfer 0.300X45°
All Dimensions in mm
b
e1
3) Package Type: SO-8EP
SO-8EP
Dim Min Max Typ
EXPOSED PAD
F
A
1.40 1.50 1.45
A1 0.00 0.13
-
b
C
D
E
0.30 0.50 0.40
0.15 0.25 0.20
4.85 4.95 4.90
3.80 3.90 3.85
1
E0 3.85 3.95 3.90
E1 5.90 6.10 6.00
b
e
F
-
-
1.27
E
2.75 3.35 3.05
2.11 2.71 2.41
0.62 0.82 0.72
N
H
L
7°
N
Q
-
-
0.35
Gauge Plane
Seating Plane
0.60 0.70 0.65
All Dimensions in mm
L
e
E0
D
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Suggested Pad Layout
Please see http://www.diodes.com/package-outlines.html for the latest version.
1) Package Type : TSOT25
C
Dimensions Value (in mm)
C
X
Y
0.950
0.700
1.000
Y1
Y1
3.199
Y
X
2) Package Type: V-DFN3030-6
Value
(in mm)
0.950
0.450
2.100
0.630
1.300
3.160
Y
Dimensions
C
X
X1
X1
Y
Y1
Y2
Y2
Y1
C - 0.329
C
X
3) Package Type: SO-8EP
X2
Value
(in mm)
1.270
0.802
3.502
4.612
1.505
2.613
6.500
Dimensions
C
X
X1
X2
Y
Y1
Y2
X1
Y1
Y2
Y
C
X
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IMPORTANT NOTICE
DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
(AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION).
Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes
without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the
application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or
trademark rights, nor the rights of others. Any Customer or user of this document or products described herein in such applications shall assume
all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated
website, harmless against all damages.
Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channel.
Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and
hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising out of, directly or
indirectly, any claim of personal injury or death associated with such unintended or unauthorized application.
Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings
noted herein may also be covered by one or more United States, international or foreign trademarks.
This document is written in English but may be translated into multiple languages for reference. Only the English version of this document is the
final and determinative format released by Diodes Incorporated.
LIFE SUPPORT
Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express
written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
A. Life support devices or systems are devices or systems which:
1. are intended to implant into the body, or
2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the
labeling can be reasonably expected to result in significant injury to the user.
B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the
failure of the life support device or to affect its safety or effectiveness.
Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any
use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related
information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its
representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems.
Copyright © 2018, Diodes Incorporated
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